This invention relates generally to clasp devices for securing a removable lid to a container, and more particularly to devices of this type which are especially intended to cooperate with the bead of a metal container lid, in order to secure it against accidental dislodgment.
Prior clasp arrangements for container lids have taken a number of different forms, with various arrangements having met with greater or lesser degrees of success. Many of the lid clamping constructions that have been proposed are of the type employing swivel-type metal handles which were secured at the sides of the containers adjacent the top, and which had hook formations that were arranged to slide over the top surface of the container lid so as to hold the latter captive. These devices were usually constituted as relatively stiff wire hooks, whereas others were made as sheet metal stampings which could be quickly punched out and thereafter bent into the desired hook-like shape. Examples of the known clasp arrangements are illustrated in U.S. Pat. Nos. 2,741,398 and 3,420,399.
Still other arrangements have been proposed, involving flexible locking straps, some of which were constituted of plastic and adapted for use with plastic containers. One such flexible lock device is illustrated in U.S. Pat. No. 3,767,110.
While many of the locking arrangements heretofore known were satisfactory for the intended use, a number of disadvantages became apparent when such devices were put into use, especially over extended periods of time.
With receptacles such as trash containers, the environment in which they were used represented an important consideration, since such units were exposed to extremes of temperatures, typically from well below 0.degree. F. to 90.degree.-100.degree. F., depending upon the particular climate where the item was being used. Coupled with these extremes in temperature, there also existed problems with highly corrosive atmospheres, these being in the nature of salt sprays adjacent ocean communities, sulfur-containing soot and smoke from nearby refineries, industrial complexes, and power-generating equipment, and extremes of moisture and humidity.
Many prior clasp arrangements involving metallic clamps and/or clips proved to be unsatisfactory in use, due to rapid degeneration of the metal of which they were constituted. Efforts to improve corrosion-resistance and resistance to weather have been made, by employing thin chrome, nickel or brass plating of the metal parts. Such coatings or platings did not solve the problems of corrosion, but instead reduced the rate of degeneration of the metal parts to a point where the devices could be considered by some people to have a reasonable life expectancy. However, even with plated parts, rust became a problem since the plating was often inadequate, and also due to the fact that where rubbing of the metal parts occurred, the plating rapidly wore off thereby exposing bare steel.
Other efforts to circumvent problems with metal corrosion have concentrated toward providing sturdy plastic parts. While this effectively solved the corrosion problem noted above, there has been a tendency for such plastic parts to tear and/or break after prolonged usage. This has been particularly true where the plastic part was molded into an unusual shape, and where substantial stresses were applied to opposite ends of the part, or to the pivot areas of the part.
Efforts which have been made to use either brass or stainless components of appreciable or large expanse have not met with much acceptance, due to the high cost of the raw materials involved with such parts, and with the difficulty in handling or processing of stainless steel.